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[Kirill Kryukov]

Hi everyone! I realized that we are still lacking reliable way to test whether an engine is using endgame tablebases or not. We need a way to test if an engine is actually accessing the tablebases. So I propose to create a set of positions for testing each piece configuration (or as many as possible).

Each position should satisfy these conditions:
1. White to move.
2. Position should be a few moves before the endgame it is testing (so some captures will follow to convert into the EGTB position). This is needed to test that an engine is really accessing the EGTB in search, not just in root.
3. Position should have only one winning move, or only one drawing move if there are no winning moves. This requirement is needed to make this test suite useful for checking bitbases too.
4. Position should be trivial to solve for an engine that probes the relevant table in its search. Finding correct move should take a few seconds for an engine accessing the endgame table being tested.
5. Position should be hard to solve without that particular table it is testing. An engine that does not have access to the table should prefer wrong moves, even if it has all other tables (with the same number of pieces).
6. Solution should be correct considering the 50 moves rule. (So that the test will be valid for both current Nalimov tables that ignore 50 moves rule and for future tables that will take it into account).
7. Position should be legal, if possible.

As you can see it is not a trivial task to construct a perfect test position for an endgame table. If you can manage to create any positions, please post here! For a start, may be some positions for testing 4-men or 5-men tables can be made.

Eventually we should have a test position for each piece configuration, so running an engine through the test suite will reveal any missing tables and test whether that engine is able to use them. Note that this test would be useful not only for Nalimov tables, but for any other format as well.

Any ideas or suggestions, and of course any positions are welcome!

Thanks!

(Crossposting from here, because I feel this is of general interest and can be useful for many)
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